This invention relates to the packaging of compressible materials such as foam, spring assemblies, mattresses and the like, and is more particularly directed to method of roll packing such compressible materials.
Conventional packaging and transportation of compressible materials such as finished mattresses, as well as foam or spring assemblies used in the manufacture of mattress products, generally involves handling of the materials in an uncompressed state. As such, the shipping and storage of the materials requires much more space than would be required if the materials were provided in a compressed state. To improve the efficiency of shipping and storage, foam mattress cores have been packaged in a compressed state by flattening the foam and sealing it in an evacuated bag. See, for example, U.S. Pat. No. 4,711,067 to Magni. This method of packaging foam cores, however, is not useful in packaging spring assemblies. In addition, storage and transportation efficiencies of the foam could be further improved by packaging the flattened cores into a tight roll.
Roll packing generally involves winding-up a desired material to form a roll and then securing the roll to prevent uncoiling of the roll during handling. In the case of compressible materials such as mattresses and foam or spring cores, it is often desired to compress the materials during the roll packing process to obtain a more dense and compact roll. Various devices have been used to achieve compression of roll packed materials. U.S. Pat. No. 3,927,504 to Forrister discloses an apparatus for rolling resilient foamed sheet material without the use of a mandrel. This machine is not useful for packaging spring assemblies and does not have the capability to package multiple units of a compressible material into a large roll. The device further does not provide for packaging a compressible material with a barrier layer between successive turns of the roll, which barrier layer is desirable to prevent adhesion between successive layers of foam.
Some roll packing systems include a mandrel for facilitating the winding of the material. For example, U.S. Pat. No. 2,114,008 to Wunderlich discloses a spring packing machine having a radially collapsible arbor for use in roll packing spring assemblies. A barrier layer between successive turns of the roll keeps the spring assemblies separate and permits easy removal of a single assembly from the roll. However, this machine is not useful for roll packing foam material due to the presence of a pressure bar which would tend to snag a compressed foam as it passed beneath. The disclosed machine also has other drawbacks. For example, to remove a finished roll, the arbor must be removed from the machine and collars must be adjusted to collapse the arbor so that the roll can be taken off the arbor. The arbor must then be replaced in the machine before another roll can be formed. Operation of the machine is thus very labor intensive and ergonomically inefficient.
The roll packing of spring assemblies, foam cores or other compressible materials onto mandrels has heretofore been a problem because the compressible material does not slide easily off of the mandrel after being rolled up. Difficulties in removing the compressible material from the mandrel are due to the material""s high friction coefficient in combination with the high compression force against the mandrel that is created when the compressed material is wound around the mandrel. When a spring or foam core is compressed onto a mandrel, the material has a natural tendency to want to expand in both radial directions, i.e., to expand radially outward from the mandrel and radially inward to the mandrel. As a result of the inward compressive force, the compressible material essentially sticks to the mandrel.
Consequently, attempting to withdraw the roll from the mandrel may damage the first few layers of the roll or cause undesirable telescoping or tearing of the rolled material as it is removed from the mandrel. Additionally, the center of the roll may implode once the roll is removed from the mandrel, causing the layers proximate the center of the roll to deform or tear.
There is thus a need for a method of efficiently roll packing compressible material such as foam or spring cores so that the roll may removed from the mandrel without damaging the rolled material or causing undesirable telescoping or tearing of the rolled material.
The present invention provides a method of roll packing a variety of compressible materials such as foam cores, spring assemblies, and fiber materials used in the manufacture of bedding or seating products, as well as finished mattresses. The machine preferably has a rotatable mandrel with collapsible cleats which permits finished roll packed materials to be easily removed from the machine by sliding the roll off of the mandrel. This type of mandrel, when used in conjunction with the present invention, permits rolled materials to be removed without any telescoping or tearing of the materials which is usually caused by binding of the roll packed material on the mandrel. However, the methods of the present invention may be used with other types of mandrel including those without retractable cleats. The present invention is especially useful in roll packing foam materials which are highly susceptible to binding against a mandrel. The methods of the present invention further permit roll packing practically any compressible material, even materials as diverse as coiled spring assemblies for mattresses and foam cores.
In accordance with the present invention, a method is provided which employs a mandrel having collapsible cleats for winding compressible materials to be roll packed. A feed table may be provided upstream of the mandrel to support and direct the compressible material to the mandrel. At least one compression roller associated with the mandrel is used to compress in-fed compressible materials in a nip between the compression roller and the mandrel as the material is being wound upon the mandrel. At least one compression roller is adjustable to vary the spacing between the mandrel and the compression roller so that the amount of compression for the in-fed materials can be varied accordingly. The apparatus used to practice of the present invention may be identical to or similar to the apparatus disclosed in applicant""s U.S. patent application Ser. No. 10/066,905, filed on Oct. 22, 2001 entitled APPARATUS AND METHOD FOR ROLL PACKING COMPRESSIBLE MATERIALS, which is fully incorporated by reference herein. However, any other apparatus may be used to practice the present invention. The invention of this application is not intended to limit the apparatus used to employ the methods of the present invention.
In further accordance with the present invention, a method for roll packing various compressible materials includes the steps of providing a mandrel rotatable about an axis and a compression roller, directing in-fed compressible materials between the mandrel and compression roller, adjusting the spacing between the mandrel and compression roller, winding the compressible material around the mandrel, stopping the mandrel when a desired amount of in-fed material has been wound upon the mandrel, and removing the roll packed material from the mandrel.
According to one aspect of the present invention, roll packing material such as paper is wrapped around the mandrel before a sheet of corrugated material is fed to the mandrel. Rotation of the mandrel winds the corrugated material around the mandrel at least one revolution. The corrugated material is then secured to itself to form a corrugated sleeve or core around the mandrel. Preferably, the corrugations of the corrugated material are oriented generally perpendicular to the rotational axis of the mandrel. A compressible material such as a continuous web of foam or other compressible material or a series of spring assemblies is fed to the mandrel along with the roll packing material. Rotation of the mandrel causes the compressible material to wind around the mandrel along with the roll packing material which forms a barrier between layers of the compressible material. When a roll of the desired size is achieved, rotation of the mandrel is stopped and the webs of roll packing material and/or compressible material cut. The roll packing material is then wrapped at least once more around the roll and secured to prevent the roll from expanding. The roll is then removed from the mandrel without the roll imploding, thereby damaging the inner layers of the roll. The corrugated sleeve or core provides a protective layer which prevents the roll from imploding.
According to another aspect of the present invention, a sheet of stiffening material, corrugated or not, is wrapped around the mandrel by rotation of the mandrel. The stiffening material may be secured to itself or to the mandrel; either way, it forms a sleeve or core around the mandrel which prevents the roll from imploding when the roll is removed from the mandrel and thereafter. Next, a compressible material such as a continuous web of foam, a series of spring assemblies or mattresses is fed to into the nip along with roll packing material. Rotation of the mandrel causes the compressible material to wind around the mandrel outside the sleeve or core along with the roll packing material which forms a barrier between layers of the compressible material. When a roll of the desired size is achieved, rotation of the mandrel is stopped and the webs of roll packing material and/or compressible material cut. The roll packing material may then be wrapped at least once more around the roll and secured to prevent the roll from expanding. The roll is then removed from the mandrel without the roll imploding, thereby damaging the inner layers of the roll.
According to another aspect of the present invention, roll packing material is wrapped once around the mandrel to cover the mandrel. Adhesive or other similar materials are then applied to the roll packing material as the roll packing material is wrapped around the mandrel. As the roll packing material is applied over the existing layers of roll packing material by rotation of the mandrel, the adhesive between the layers of roll packing material drys. The result is a laminated sleeve or core immediately adjacent the mandrel. Once a sufficient number of layers of roll packing material have been wrapped around the mandrel, application of the adhesive is stopped. However, the roll packing material continues to be wrapped around the mandrel along with the compressible material. A compressible material such as a continuous web of foam or a series of spring assemblies is fed to the mandrel along with the roll packing material. Rotation of the mandrel causes the compressible material to wind around the mandrel along with the roll packing material which forms a barrier between layers of the compressible material. When a roll of the desired size is achieved, rotation of the mandrel is stopped and the webs of roll packing material and/or compressible material cut. The roll packing material is then wrapped at least once more around the roll and secured to prevent the roll from expanding. The roll including the sleeve or core is then removed from the mandrel without the roll imploding, thereby damaging the inner layers of the roll. The laminated sleeve or core provides a protective layer which prevents the roll from imploding.
Accordingly, the invention provides a method for roll packing a variety of compressible materials and which is preferably used in conjunction with a mandrel having collapsible cleats that facilitates the easy removal of finished rolls without tearing, telescoping, or otherwise damaging the roll packed material. These and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and description.